The present invention relates generally to refrigeration compressors and more particularly to hermetic type refrigeration compressors in which the compressor and driving motor are disposed interiorly of a hermetically sealed shell.
In hermetic compressors, it is often desirable to provide a shroud over one end of the driving motor for various reasons, such as to obtain a suction gas muffling effect therefrom and/or to serve as a conduit member for insuring that all of the suction gas entering the compressor is passed over at least a portion of the motor to thereby serve to cool same. Typically such compressors have a housing containing the actual compressing means, usually a rotary or reciprocating piston and cylinder, and in which a crankshaft is rotatably journaled. Generally, the crankshaft extends outwardly from one end of this housing and has a motor rotor secured thereto. A motor stator surrounds the rotor and will generally be secured to the housing such as by a plurality of bolts extending longitudinally through or adjacent the stator. Manufacturing tolerances within the various components of such compressors often result in the rotor position varying slightly from one compressor to another, thus necessitating that each stator be individually positioned with respect to the rotor to set the air gap therebetween. While setting this air gap may not present a problem in those hermetic compressors which do not employ a shroud over the open end of the motor, this can be a relatively difficult task in those compressors having such a shroud because the shroud covers the stator fasteners. In such cases the shroud may be secured to the stator or housing structure by either a press fit or providing additional fasteners. When a press fit arrangement is employed, it is generally necessary to machine a seating shoulder portion on the stator or housing to assist in locating the shroud thus incurring additional expense in both time and labor to perform this operation. Further, the shroud must be accurately formed and sized to the particular stator or housing to insure a snug frictional engagement therebetween so as to prevent vibrations from dislodging the shroud during operation of the compressor. Similarly, the use of additional fasteners engaging the stator or housing also require an additional machining operation to provide openings therein to receive these fasteners. Further, additional time and expense will be required to assemble these fasteners.
Shrouds are generally employed in such compressors to attenuate suction noise emanating from the pressure pulses produced by the compressor as well as to direct substantially all of the suction gas over at least a portion of the motor for cooling. Thus, it is necessary to provide an inlet opening in the shroud. In one such arrangement, a conduit is provided through the shell to deliver suction gas directly into the shroud. This has the disadvantage, however, in that lubricant entrained in the suction gas will be directed into the motor compartment and may be carried into the compressor itself. Similarly any liquid refrigerant may also flow directly into the motor compartment. These liquids may cause slugging of the compressor as well as placing an undue strain upon the motor.
In other arrangements a suction gas inlet is located in the side of the shell a substantial distance from the shroud, and an inlet opening is provided somewhere through the shroud wall. This construction has the advantage that it employs the volume between the outer shell and motor compressor unit as an expansion chamber to help separate the lubricant and any liquid refrigerant; however, because of the length of the suction gas flow path, some losses will occur.
The present invention provides a shroud and means for attaching this shroud to the stator structure which overcome the problems associated with these prior constructions. In the present invention, a fastening device having an upwardly extending flange portion is placed on top of the motor stator structure and secured thereto by the same bolts employed to secure the stator structure to the compressor housing portion. The flange portion of the fastening device may then be folded over portions of the shroud member after the air gap has been properly set. As the shroud does not require any additional fasteners nor does it depend upon loosening and removal of the stator securing bolts subsequent to the setting of the air gap, assembly time is substantially reduced. Further, no additional high precision machining operations are required on either the housing or stator because the fastening device is both positioned and retained by the stator securing bolts.
Additionally, the present invention resides in the optional provision of a suction gas directing member on a vertically extending side wall portion of the motor shroud, the gas directing member being aligned with a suction gas inlet through the shell. In one embodiment, the suction gas flows across the end windings of the motor and through conduit members extending to and communicating with the compressor means in the housing to which the motor is secured. In another embodiment, the suction gas flows through the air gap between the rotor and stator structure of the motor downwardly and through a passage means provided in the housing to the compressor. In both embodiments, the suction gas directing member is positioned in an aligned spaced relationship with the suction inlet in the shell so as to smoothly direct the suction gas into the shroud while also providing an expansion space therebetween which effectively separates the oil therefrom thus preventing such lubricant from interfering with or otherwise affecting the operation of the motor and/or compressor.
Additional advantages and features of the present invention will become apparent from the following detailed description of the preferred embodiment taken in conjunction with the attached drawings and the claims appended hereto.